SAXS structural characterization of a liposome-based drug product

The application of liposomes for targeted drug delivery has had a major impact in many biomedical areas. Liposomes are attractive as a delivery system due to their flexibility in their physicochemical and biophysical properties.

Liposomal drug delivery systems are effective for the targetted delivery of small-molecule drugs, vaccines and genes. The physical characterization of drug-loaded liposomes becomes more and more important and is required by regulatory entities to obtain marketing autorization for a drug product.

At DANNALAB, with the use of Small Angle X-Ray Scattering (SAXS), we are capable of reconstructing the structure of a liposome carrier, either alone- or loaded with a drug.

Below, Figure 1 presents the measured differential SAXS pattern of a liposomal drug formulation containing an API nanocrystal. SAXS liposome drug differential pattern
Figure 2 presents an example showing the physical model we use for the characterization of a liposomal drug formulation.

SAXS liposomal drug model

Parameters of the model are refined to achieve the best fit between the measured differential SAXS pattern and the pattern calculated from a model.

From the model presented in Figure 2, we can obtain information about the thickness and density of the lipid bi-layers, the PEG corona and the dimensions of a loaded nanocrystalline drug. An example of the list of parameters is presented in Figure 3.

SAXS liposomal drug model parameters